The present invention relates to a tube for use in a pelleting centrifuge rotor. 2. Description of the Prior Art
A centrifugal pelleting operation is the usual procedure used to separate solid particles, such as cells, suspended in a liquid supernatant. In a pelleting operation a container, typically a test tube, having the liquid suspension therein is placed in a cavity of a centrifuge rotor and subjected to a centrifugal force field. Centrifugal force causes the solid material to separate from the liquid supernatant and to deposit itself in a clump, called a pellet, on the wall of the tube. When the liquid supernatant is withdrawn from the tube the pellet may be removed for analysis or resuspended for further processing.
The tubes that are commonly used in pelleting applications within a pelleting rotor are circular at every cross section taken perpendicular to the tube axis along the tube's entire axial length. This standard test tube shape imparts a conical end to the tube that makes difficult both the location of the pellet on the bottom of the tube bottom as well as the removal of the all of supernatant from the tube.
The problem of pellet location is made somewhat easier when a capped microtube is used as the container, inasmuch as the tab on the cap provides a convenient feature that can be used to orient the microtube within the rotor cavity.
In another aspect, it is sometimes the case that the volume of the liquid suspension available for processing is limited. In these instances, rather than diluting the available volume of the suspension, it may be necessary or desirable to use a separate adapter within the tube in order to have the suspension fill more completely the interior volume of the tube.
In view of the foregoing it is believed advantageous to provide a tube having a shape that facilitates both the location of the pellet within the tube and the removal of supernatant from the tube. It is also believed advantageous to provide a tube that has a constricted interior volume thereby to present a volume that is sized more closely to the available volume of the suspension.